Catalytic cracking and in situ combustion process for producing hydrocarbons



Nov. 19, 1968 R. E. LINDSAY CATALYTIC CRACKING AND IN SITU COMBUSTIONPROCESS FOR PRODUCING HYDROCARBONS Filed Sept. 2, 1966 56 54 3 52 S fiJ48 40 44 HYDROCARBON SEPARATOR RECOVERY SYSTEM FLUE GAS as 46 50 I r-22 STEAM I l CATALYST SEPARATION 28 r "I CATALYST 26 rl l- REGENERATIONVi g I AIR /COMBUST|ON ZONE GASES COM BUST ION ZONE A 7' TORNEYS UnitedStates Patent 3,412,011 CATALYTIC CRACKING AND IN SITU COMBUSTIONPROCESS FOR PRODUC- ING HYDROCARBONS Robert E. Lindsay, Bartlesville,Okla., assignor to Phillips Petroleum Company, a corporation of DelawareFiled Sept. 2, 1966, Ser. No. 577,062 8 Claims. (Cl. 208-113) ABSTRACTOF THE DISCLOSURE A process for upgrading hydrocarbons produced in vaporform by in situ combustion within the subterranean oil stratumcomprising contacting a vaporous hydrocarbon with a fluidized crackingcatalyst within a production well, separating the catalyst from theresulting eflluent, recovering the upgraded hydrocarbons, and recyclingthe catalyst to the subterranean oil stratum to crack the vaporoushydrocarbons.

This invention relates to a process for catalytically cracking vaporoushydrocarbons from a reverse in situ combustion operation in a productionwell thru which hydrocarbons are being produced from the in situcombustion operation.

Production of hydrocarbons from an oil stratum by reverse burning insitu combustion is being practiced in the petroleum industry. Theprocess comprises initiating combustion 'by any suitable means around aproduction well penetrating the oil stratum and feeding air to theresulting combustion zone from one or more offset injection wells,preferably a ring of wells surrounding the production well. The injectedair arriving in the combustion zone propagates this zone toward theinjection wells and away from the production well, leaving burned-outrock or sand behind the combustion front as it progresses thru thestratum. The combustion process is effected in the temperature range ofabout 750 to 1500 F., usually at least about 1000 F., so that theproduced hydrocarbons are in vapor form as they enter the productionwell. There is substantial upgrading of the crude oil in this process.In one reverse burning in situ combustion operation in an oil fieldcontaining API gravity oil, the produced oil was upgraded to about APIgravity.

It is desirable to upgrade the hydrocarbons produced from the in situcombustion operation still further. This invention is concerned withsuch a process.

Accordingly, it is an object of the invention to provide a process forupgrading hydrocarbons produced from a reverse burning in situcombustion process While the hydrocarbons are at an elevated temperaturein the cracking range and in the production well. Another object is toutilize the heat of combustion developed in the in situ production ofoil in the cracking of heavier hydrocarbons in the product stream tolighter, more valuable hydrocarbons. A further object is to provide aprocess for catalytically cracking hot vaporous hydrocarbons from areverse burning in situ combustion operation which makes use of the heatof combustion developed during the in situ combustion operation. Otherobjects of the invention will become apparent to one skilled in the artupoh consideration of the accompanying disclosure.

A broad aspect of the invention comprises subjecting the hot vaporouseffluent from a reverse burning in situ combustion operation tocatalytic cracking in contact with a fluidized cracking catalyst withinthe production well thru which the hydrocarbons from the in situcombustion operation are being produced. A selected cracking catalyst,such as silica-alumina, is injected into the vaporous hydrocarboneffluent from the in situ combustion opoperation either in thecasing-tubing annulus or in the tubing string leading from the oilstratum thru the well head. However, it is preferred to inject thefluidized catalyst in a selected gas, such as normally gaseoushydrocarbons or steam, thru the tubing string into the productioneffluent rising thru the annulus surrounding the tubing.

Any conventional cracking catalyst may be utilized in the process whichis amenable to fluidization in a gas. Silica-alumina is the mostcommonly utilized cracking catalyst in conventional cracking operationsbut the invention does not lie in a specific catalyst and any crackingcatalyst which operates satisfactorily in finely divided fiuidizableform is within the scope of the invention.

The cracked effluent carrying the catalyst in suspension is passed thrua separation zone to recover the catalyst and the catalyst is passed toa catalyst regeneration step which involves burning off the carbonaceousdeposits, resulting from the cracking operation, with air at atemperature in the range of about 950-1 F. The resulting hot regeneratedcatalyst is then admixed with the carrier gas for transport to the wellvia the tubing or the annulus into the ascending column of in situcombustion effluent.

One aspect of the invention comprises separating a normally gaseousstream of hydrocarbons from the cracked hydrocarbon eflluent andutilizing this stream for suspending and transporting the regeneratedcatalyst to the cracking zone within the production well. It is alsofeasible to inject steam into the hydrocarbon stream serving as atransport gas or to use steam entirely as the transport gas.

A more complete understanding of the invention may be had by referenceto the accompanying schematic drawing, which is an elevation in partialsection of an arrangement of apparatus in combination with a productionwell in a carbonaceous stratum undergoing inverse in situ combustion foreffecting the process of the invention.

Referring to the drawing, an oil stratum 10 is penetrated by aproduction well 12 which is provided with a casing 14 extending thru thestratum and perforated therein and with a tubing string 16. Hightemperatureresistant steel should be utilized in the casing within thestratum and the lower end of the turning string. In some reverse in situcombustion operations, a porous refractory liner is utilized in theproduction well to withstand the temperatures downhole.

A burned-out recovery zone at the stage of operation depicted is boundedby line 18. The combustion front 20 is moving radially away from well 12toward a ring of offset injection wells (not shown) and the area withinthe confines of line 18 comprises hot burned-out sand thru which theproduced hydrocarbons and combustion gases flow to the production well.Well 12 may also represent one well in a line of production wellsflanked on each side by a line of injection wells.

In the embodiment of the invention illustrated in the drawing, casing 14extends above ground a short but substantial distance and connects witha catalyst separation vessel 22 which is provided with a shield orbaffie 24 for disengaging the catalyst from the product gas stream. Thecatalyst drops to the bottom of vessel 22 and is withdrawn thru line 2-6which delivers the catalyst to a regeneration vessel 28 for contactingwith air or diluted air introduced to the bottom of the vessel thru line30 under the impetus of pump 32. The regenerated catalyst flows out line34 and the flue gas is vented thru line 36.

The product gas passes from the top of vessel 22 via line 38 intocyclone separator 40 which knocks down catalyst fines still remaining inthe product gas so that these fines are delivered via conduit 43 to therecovered catalyst in the bottom of vessel 22. The substantiallycatalyst-free product gas passes from separator 40 thru line 44 tohydrocarbon recovery system 46 where a separation is made into normallygaseous hydrocarbons which are recovered thru line 48, normally liquidhydrocarbons recovered thru line 50, and nonhydrocarbon gases and H thruline 52. A portion of the normally gaseous hydrocarbons may be recoveredthru line 54 as product and another stream of these gases is passed vialine 56 to tubing string 16 at the well head, carrying a suspension ofcatalyst from line 34. Steam or other transport gas may be introducedthru line 58 to line 46 at a suitable locus as upstream of line 34. Anindirect heat exchange vessel 60 is positioned in line 56 for regulatingthe temperature of the transport gas in operation in which suchregulation is needed. Regenerated catalyst can be withdrawn fromregenerator 28, heat exchanged, and recycled to the regenerator 28 fortemperature control of the system (not shown). Also, the amount ofregenerated catalyst flowing to the system thru conduit 34 can becontrolled to control the temperature of the system.

A thermocouple 62 downhole in the incipient cracking zone is connectedby cable 64 with a temperature recorder 66 above ground for the purposeof determining the temperature downhole in the cracking zone. The sensedcracking temperature can be utilized to control the temperature of thecatalyst suspension downstream of line 34 by either adding heat to orextracting heat from the gaseous stream in line 56 upstream of line 34as by heat exchanger 60 and/or gas introduced thru line 58 and/or byheat exchange of a portion of the regenerated catalyst and/or amount ofregenerated catalyst used. It is also feasible to analyze the hoteffiuent in line 44 to determine the extent of cracking and adjust thecracking temperature downhole to efiect the desired amount of cracking.One method comprises analyzing the efliuent for olefin concentration orH concentration as an indication of the depth of cracking and regulatingthe temperature of cracking in response thereto so as to provide thedesired amount of cracking.

The following example illustrates a preferred method of operation but itis not to be construed as unnecessarily limiting the invention.

SPECIFIC EXAMPLE Range Specific Rcgenerator (28):

Pressure, p.s.i.g -50 Temperature, F 1, 0504, 1, 100 Tubing (16): Top:

Pressure, p.s.i.g 3-48 18 Temperature, F 950-1, 150 l, 000 Bottom:

Pressure, p.s.i.g (A) 218 Temperature, F (A) 980 Length, feet (A) 400Annulus (14):

Top:

Pressure, p.s.i.g 20 Temperature, F 900 Bottom:

Pressure, p.s.1.g (A) 80 Temperature, F (A) 980 In Situ Zone:

Pressure, p.s.i.g (A) 300 Temperatur F (A) 1, 200 Catalyst/Hydrocarbon(C), Wt. Ratio 2:1 to 10:1 4:1 Conversion, Vol. Percent Hydrocarbon:

API at F. before combustion 5 .0 API at 60 F. after combustion 25 .0

Liquid Vol. Percent at 60 F.

Hydrocarbon Cracked Products:

Butane and Lighter (measured as liquid) 14 Gasoline (400 F., E.P.) 41Cycle Oils 50 Total (B) Certain modifications of the invention willbecome apparent to those skilled in the art and the illustrative detailsdisclosed are not to be construed as imposing unnecessary limitations onthe invention.

I claim:

1. A process for upgrading hydrocarbons from an in situ combustionprocess conducted in a subterranean oil stratum penetrated by aproduction well having a casing and a tubing string leading to saidstratum, wherein hydrocarbons produced in vapor form around saidproduction well at a temperature of at least 750 F. are recoveredthrough said production well by the steps of:

(a) passing said hot produced hydrocarbons through one of the tubing andthe casing-tubing annulae in admixture with a fluidized solidparticulate cracking catalyst to substantially crack heavierhydrocarbons to lighter hydrocarbons, the cracking occurring in theabsence of added hydrogen;

(b) separating catalyst from the vaporous effluent from said productionwell;

(c) recovering hydrocarbons from the effiuent of step (b); and

(d) injecting into the other of the tubing and easingtubing annulae atthe production well head a hot gaseous suspension of the catalyst ofstep (a) whereby said catalyst is introduced to said hot hydrocarbonsdownhole.

2. The process of claim 1 including the steps of:

(e) recovering a stream of normally gaseous hydrocarbons from thehydrocarbons of step (c);

(f) burning deposited coke 011 the catalyst recovered in step (b) toregenerate same; and

(g) suspending regenerated hot catalyst of step (f) in the stream ofnormally gaseous hydrocarbons of step (e) to provide the suspension ofstep (d).

3. A process for upgrading hydrocarbons from a reverse in situcombustion process conducted in a subterranean oil stratum penetrated byan injection well and a production well having a casing and a tubingstring leading to said stratum, wherein combustion is initiated aroundsaid production well, the resulting combustion zone is advanced throughsaid stratum toward said injection well by injecting air through saidinjection well to feed said combustion, and produced hydrocarbons invapor form at a temperature of at least 750 F. are recovered throughsaid production well, which comprises the steps of:

(a) passing said hot produced hydrocarbons through one of the tubing andthe casing-tubing annulae in admixture with a fluidized solidparticulate cracking catalyst to substantially crack heavierhydrocarbons to lighter hydrocarbons, the cracking occurring in theabsence of added hydrogen;

(b) separating catalyst from the vaporous effluent from said productionwell;

(c) recovering hydrocarbons from the effluent of step (d) injecting intothe other of the tubing and easingtubing annulae at the production wellhead a hot gaseous suspension of the catalyst of step (a) whereby saidcatalyst is introduced to said hot hydrocarbons downhole;

(e) recovering a stream of normally gaseous hydrocarbons from thehydrocarbons of step (c);

(f) burning deposited coke off the catalyst recovered in step (b) toregenerate same; and

(g) suspending regenerated hot catalyst of step (f) in the stream ofnormally gaseous hydrocarbons of step (e) to provide the suspension ofstep (d).

4. The process of claim 3 including the steps of:

(h) sensing the temperature of the cracking reaction in step (a); and

(i) regulating the temperature of the catalyst suspension in step (d) soas to maintain a selected reaction temperature in the range of 750 to950 F.

5. The process of claim 3 wherein the temperature of the hot suspensionof step (g) is adjusted to maintain a selected cracking temperature instep (a) in the range of 750 to 950 F.

6. The process of claim 4 wherein the sensed temperature issubstantially below the selected temperature and said suspension in step(d) is introduced at a substantially higher temperature than said hothydrocarbons at initiation of cracking.

7. The process of claim 4 wherein the temperature of the hothydrocarbons is substantially above the selected cracking temperatureand said suspension in step (d) is cooled to a temperature substantiallybelow said selected temperature so as to effect reaction at saidselected temperature.

8. The process of claim 3 wherein steam is added to said suspension instep (g).

References Cited UNITED STATES PATENTS DELBERT E. GANTZ, PrimaryExaminer.

ABRAHAM RIMENS, Assistant Examiner.

